# How do you define a snowflake schema?

## How do you define a snowflake schema?

In computing, a snowflake schema is a logical arrangement of tables in a multidimensional database such that the entity relationship diagram resembles a snowflake shape. The snowflake schema is represented by centralized fact tables which are connected to multiple dimensions.

Which is wrong about snowflake schema?

First statement is false as in snowflake schema each dimension is represented by multi-dimensional tables but this statement is true for star schema as each dimension in star schema represents single dimension.

What is a snowflake dimension?

The snowflake schema consists of one fact table that is connected to many dimension tables, which can be connected to other dimension tables through a many-to-one relationship. Tables in a snowflake schema are usually normalized to the third normal form. Each dimension table represents exactly one level in a hierarchy.

### How do you identify dimensions and attributes?

To identify dimensions, you perform the following steps:

1. Use the grain definition to locate possible dimensions.
2. List all of the dimensions that are associated with this grain. Define the level of detail to include in that dimension.
3. Create surrogate keys for the primary keys of the dimensions.

Which one is a characteristic of snowflake schema?

Characteristics of snowflake schema: The dimension model of a snowflake under the following conditions: The snowflake schema uses small disk space. It is easy to implement dimension that is added to the schema. There are multiple tables, so performance is reduced.

What are dimension and fact tables?

Fact Table vs Dimension Table Comparison Table

Characteristics Fact Table Dimension Table
Creation Time A fact table is created after dimension tables are created. The dimension table needs to be created first.
Schema Structure There is less number of fact tables in a schema. There is a number of dimension tables in a schema.

#### What are junk dimensions?

A Junk Dimension is a dimension table consisting of attributes that do not belong in the fact table or in any of the existing dimension tables. The nature of these attributes is usually text or various flags, e.g. non-generic comments or just simple yes/no or true/false indicators.

Is snowflake schema normalized?

The snowflake schema is a fully normalized data structure. Dimensional hierarchies (such as city > country > region) are stored in separate dimensional tables. On the other hand, star schema dimensions are denormalized.

Is snowflake a dimensional model?

## What is schema and explain star and snowflake schema?

Star and snowflake schema designs are mechanisms to separate facts and dimensions into separate tables. Snowflake schemas further separate the different levels of a hierarchy into separate tables. In either schema design, each table is related to another table with a primary key/foreign key relationship.

What is a dimensional attribute?

A dimension attribute is a column in a dimension table. Each attribute describes a level of summary within a dimension hierarchy. The dimension elements define the hierarchical relationships within a dimension table. The dimension attributes describe the dimension elements in terms that are familiar to users.